EN 993-6-1995 pdf download.Methods of test for dense shaped refractory products Part 6: Determination of modulus of rupture at ambient temperature.
This Part of EN 993 specifies a method for the determination of the modulus of rupture of dense and insulating shaped refractory products at a,nhient temperature, under conditions of a constant rate of increase of stress.
The method relates primarily to shaped and fired refractories. If it is to be applied to chemically bonded or tar-bonded bricks, they will usually require some form of preliminary heat treatment. This preliminary treatment, the details of which are outside the scope of this standard, is a matter of agreement between the interested parties and shall be described in the test report.
2 Definition
For the purposes of this Part of EN 993, the following definition applies.
modulus of rupture
the maximum stress that a prismatic test piece of specified dimensions can withstand when it is bent in a three-point bending device
3 Principle
Loading of test pieces of the product to be tested at a constant rate of increase of stress until failure occurs.
4 Apparatus
4.1 Loading device
4.1.1 The loading device shall have three bearing edges, two to support the test piece and one for the application of the load (see Figure 1). The three edges shall have a radius of curvature in accordance with the requirements given in Table 1 and shall be of length not less than 5 mm greater than the breadth (b) of the test piece. The line contact of the three edges shall be parallel to each other in a direction perpendicular to the length and the plane of the breadth of the test piece. Two supporting edges shall rest on an intermediate bearing piece, cylindrical on its lower surface, so that each edge may rotate independently in a vertical plane to accomodate any slight twist in the test piece. Alternatively, one supporting edge may be fixed, with the other supporting edge and the loadbearing edge being capable of rotation in a vertical plane. The distance between the two supporting edges shall be in accordance with Table 2 and the Ioadbearing edge shall be positioned equidistantly, at ±2 mm from each supporting edge. (See Figure 1 and Figure 2).
4.1.2 The loading device shall be capable of applying a load uniformly across the centre of the test piece and of increasing it at a uniform rate. A means shall be provided of recording or indicating the load at failure with an accuracy of± 2 %.
4.2 Drying oven, capable of being controlled at (110 ± 5) °C.
5 Preparation of test pieces
5.1 Number
5.1.1 The number of items (for example, bricks shapes, nozzles) to be tested shall be determined by agreement between the interested parties.
5.1.2 If test pieces are cut out of bricks or blocks, the same number shall he cut from each one, in order to facilitate statistical analysis.
NOTE The number of test pieces to be cut from each item (which detail is outside the scope of this standards is a matter for agreement between the interested parties. It should be stated in the test report.
5.2 Shape and sixe
Each test piece shall be a whole standard rectangular brick (230 mm x 114 mm x 76 mm or 230 mm X 114 mm X 64 mm) or one of the other sizes shown in Table 1.
5.3 Preparation
5.3.1 Standard size bricks (see 5.2) shall be tested as received.
5.3.2 If test pieces are cut out of bricks, it shall be done in such a way that, if the direction in which the brick was pressed is known, the upper longitudinal face in the testing position (the face in compression) is Parallel to, or coincides with, one of the original faces of the brick perpendicular to the direction of pressing.
NOTE Cutting with a continuous rim diamond wheel is recom mended. If a serrated rim wheel is used. the edges of the cut where the wheel emerges are often frayed: it is therefore recommended that such a wheel should enter the face of the brick that is to form the tensile face of the test piece during the test.
5.3.3 The direction of pressing, if known, shall be marked on the test piece.EN 993-6-1995 pdf download.